用QR阻尼法分析固有频率,中间突然出现几阶零,是怎么回事?
如题,结果如下,*****INDEX OF DATA SETS ON RESULTS FILE*****
SET TIME/FREQ(Damped) TIME/FREQ(Undamped) LOAD STEPSUBSTEPCUMULATIVE
10.0000 0.87601E-03j 0.87601E-03 1 1 1
0.0000 -0.87601E-03j
2-0.99481 176.03 j 166.39 1 2 2
-0.99481 -176.03 j
3 -6.6455 398.26 j 387.90 1 3 3
-6.6455 -398.26 j
4 -3.5851 471.78 j 431.36 1 4 4
-3.5851 -471.78 j
593.844 547.86 j 462.87 1 5 5
93.844 -547.86 j
6111.83 639.00 j 539.80 1 6 6
111.83 -639.00 j
7118.75 647.44 j 559.41 1 7 7
118.75 -647.44 j
8115.98 652.09 j 578.01 1 8 8
115.98 -652.09 j
991.739 671.27 j 590.32 1 9 9
91.739 -671.27 j
1048.595 684.00 j 607.12 1 10 10
48.595 -684.00 j
11 -48.703 853.61 j 633.18 1 11 11
-48.703 -853.61 j
12 -88.035 906.26 j 640.53 1 12 12
-88.035 -906.26 j
13 -132.42 1008.0 j 654.70 1 13 13
-132.42 -1008.0 j
14 -1073.6 0.0000 j 691.32 1 14 14
-1073.6 0.0000 j
15 -1099.2 0.0000 j 731.67 1 15 15
-1099.2 0.0000 j
16 -1143.4 0.0000 j 770.30 1 16 16
-1143.4 0.0000 j
17 -94.980 1141.3 j 1005.3 1 17 17
-94.980 -1141.3 j
18 -1214.1 0.0000 j 1030.0 1 18 18
-1214.1 0.0000 j
19 -1246.5 0.0000 j 1183.4 1 19 19
-1246.5 0.0000 j
20 -88.681 1264.0 j 1281.0 1 20 20
-88.681 -1264.0 j
21 -1285.0 0.0000 j 1425.0 1 21 21
-1285.0 0.0000 j
22 -166.54 1409.7 j 1503.5 1 22 22
-166.54 -1409.7 j
23 -645.31 1408.4 j 1552.9 1 23 23
-645.31 -1408.4 j
24 -1551.9 0.0000 j 1651.2 1 24 24
-1551.9 0.0000 j
25 -95.210 1575.9 j 1787.6 1 25 25
-95.210 -1575.9 j
26 -121.03 1664.5 j 1833.4 1 26 26
-121.03 -1664.5 j
27 -89.852 1692.9 j 1887.9 1 27 27
-89.852 -1692.9 j
28 -75.075 1905.6 j 1959.6 1 28 28
-75.075 -1905.6 j
29 -111.77 1946.5 j 2115.3 1 29 29
-111.77 -1946.5 j
30 -95.822 2116.1 j 2246.5 1 30 30
-95.822 -2116.1 j
31 -2325.1 0.0000 j 2473.8 1 31 31
-2325.1 0.0000 j
32 -71.240 2364.8 j 2550.0 1 32 32
-71.240 -2364.8 j
33 -97.207 2403.0 j 2623.8 1 33 33
-97.207 -2403.0 j
34 -58.966 2537.0 j 2685.5 1 34 34
-58.966 -2537.0 j
35 -45.153 2596.6 j 2830.4 1 35 35
-45.153 -2596.6 j
36 -2670.1 0.0000 j 2954.1 1 36 36
-2670.1 0.0000 j
37 -44.071 2783.0 j 2995.6 1 37 37
-44.071 -2783.0 j
38 -49.736 2910.2 j 3233.2 1 38 38
-49.736 -2910.2 j
39 -36.178 2978.9 j 3433.7 1 39 39
-36.178 -2978.9 j
40 -3164.9 0.0000 j 3515.5 1 40 40
-3164.9 0.0000 j
41 -3202.6 0.0000 j 3558.9 1 41 41
-3202.6 0.0000 j
42 -11.244 3221.7 j 3575.3 1 42 42
-11.244 -3221.7 j
43 -42.853 3378.8 j 3968.6 1 43 43
-42.853 -3378.8 j
44 -3386.3 0.0000 j 4090.4 1 44 44
-3386.3 0.0000 j
45 -45.937 3462.2 j 4152.3 1 45 45
-45.937 -3462.2 j
46 -29.327 3530.4 j 4251.3 1 46 46
-29.327 -3530.4 j
47 -29.112 3542.5 j 4488.6 1 47 47
-29.112 -3542.5 j
48 -36.254 3933.3 j 4578.3 1 48 48
-36.254 -3933.3 j
49 -3989.6 0.0000 j 4643.0 1 49 49
-3989.6 0.0000 j
50 -4018.8 0.0000 j 4666.4 1 50 50
-4018.8 0.0000 j
比如说14~16,出现了虚部,即固有频率为零,这是怎么回事呢?
回复 #1 sheman2001 的帖子
出现虚部可能有下面的原因：k矩阵不是对称矩阵；
阻尼的影响；
没有消除刚体自由度；
没有消除自由度相等的情况； 如果计算后结果，频率突然降低，然后又增大，这是什么原因呢？如
1 320Hz
2 280Hz
3400Hz
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